Method for preparing diboron tetrafluoride



3,186,7tl8 METHOD FOR PREPARING DIBORON TETRAFLUORIDE Allen L. McCloslrey, Costa Mesa, Harold M. Manasevit, Anaheim, and Robert J. Brotherton, Fullerton, Calif., assignors to United StatesBorax & Chemical Corporation, LosAngeles, Calih, a corporation of Nevada No Drawing. Original application Mar. 22, 1961, Ser. No. 97,473. Divided and this application Sept. 23, 1964, Ser. No. 398,789

1 Claim. (Cl. 23-22%) By means of the present invention, diboron tetrafiuoride I may now be produced economically in commercial quantities.

It is therefore the principal object of the present invention to provide a new and economically desirable method for the preparation of diboron tetrafluoride.

Other objects of this invention will appear as the description proceeds.

United States Patent To the accomplishment of the foregoing and related ends, said invention then comprises the features herein after fully described and particularly pointed out in the claim, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

Broadly stated, the present invention comprises the method for preparing diboron tetrafiuor ide which comprises reacting a material selected from the group consisting of boron monoxide and B (OR) with sulfur tetrafiuoride at a temperature below ambient temperature in a substantially anhydrous oxygen-free atmosphere and recovering substantially pure diboron tetrafluoride, wherein R is a material selected from the group consisting of hydrogen, unsubstituted saturated aliphatic hydrocarbon radicals, substituted saturated aliphatic hydrocarbon radicals having aromatic hydrocarbon substituents, unsubstituted aromatic hydrocarbon radicals, and substituted aromatic hydrocarbon radicals having unsubstituted saturated aliphatic hydrocarbon substituents.

The reactions of the foregoing broadly stated paragraph can best be illustrated by the following general equations:

where R is a material as described above.

We have found that at above ambient temperatures, side reactions occur and thus lower temperatures are preferable. Therefore, in the preferred embodiment of our invention we use temperatures of from about 0 C. to about l0=tl C.

The best yields are obtained when about stoichiometric amounts of reactants are used. However, the reaction readily proceeds when more or less than stoichiometric amounts of sulfur tetrafluoride is present. Diboron tetrafluoride has been produced from reactions wherein from about 15% less to about 15% excess of the stoichiometric amount of sulfur tetrafluoride was used. However, as

noted above, stoichiometry is preferred. p

The following list is illustrative of the diboron compounds whichare applicable to the present invention:

Tetrahydroxydi-boron Tetramethoxydiboron Tetraethoxydiboron Tetraisopropoxydiboron Tetra(t-butoxy) dib oron Tetra- 2-hexyloxy diboron Tetran-octyloxy) diboron Tetra- (Z-phenylethoxy) diboron Tetra- 3-phenylbutoxy)diboron Tetra phenoxydiboron Tetraot-naphthoxy) diboron Tetra quinolin-S-oxy) diboron Tetra (2,3-diethylphenoxy) diboron Tetr al-phenylpropoxy) diboron It is to be clearly understood that the foregoing list is only a partial enumeration of the diboron compounds which are applicable to the present invention and is in no way intended to limit the invention. 7

So that the present invention can be more clearly understood, the following examples are given for illustrative purposes.

I. Boron'rnonoxide and about 5% in excess of the stoichiometric amount of sulfur tetrafiuoride were mixed at about C. or below in an anhydrous oxygen-free system. The temperature of the'reaction mixture was held at about 80 C. for a period of 16 hours. The reaction mass was then warmed slowly to room temperature and the volatile constituents separated by fractional condensation with the subsequent recovery of diboron tetrafluoride. The diboron tetrafluoride was identified by vapor pressure, molecular weight, melting point and infrared spectrum determinations which were substantially identical with the known data for diboron tetrafiuoride.

H. stoichiometric amounts (as shown in the foregoing equations) of tetrahydroxydiboron and sulfur tetrafluoride were mixed below -60 C. in an anhydrous oxygen-free system. The temperature of the reaction mixture was adjusted to about 60 C. and held there for a period of 8 hours. The reaction mass was then warmed slowly to room temperature and the volatile constituents separated byv fractional condensation with the subsequent recovery of diboron tetrafiuoride. The diboron tetrafluoride was identified by vapor pressure, molecular weight, melting point and infrared spectrum determinations which were substantially the same as the known data for diboron tetrafluoride.

TH. Tetraethoxydiboron and'about 12% less than the stoichiometric amount of sulfur tetrafiuoride (as shown in the foregoing equations) were mixed at 80 C. or below, in an anhydrous oxygen-free system. The temperature of the reaction mixture was then raised to about 80 C. and held there for a period of 17.5 hours. The reaction mass was then warmed slowly to room temperature and the volatile constituents separated by fractional condensation with the subsequent recovery of diboron tetrafiuoride. The diboron tetrafluoride was identified as in the foregoing examples and was found to be substantially identical with the known data for diboron tetrafluoride.

Diboron tetrafiuoride, as stated previously, has many desirable properties which provide this compound with a variety of uses. Dibron tetrafluoride is a very effective dehydrating agent reacting with water to yield hydrogen fluoride and it is also an extremely active antioxidant. When heated to high temperatures in a reducing atmosphere it decomposes and elemental boron is produced. Diboron tetrafiuoride can also be used for the prepara- 13 tion of polymers. Diboron tetrafluoride also reacts with unsaturated compounds producing diboronic acid derivatives which are very difficult or impossible to prepare by conventional processes.

Other modes of applying the principle of the invention may be employed, change being made as regards the detailsdescribed, provided the features stated in the following claim or the equivalent of such be employed.

We, therefore, particularly point out and distinctly claim as our invention:

The method for preparing diboron tetrafiuoride which comprises reacting boron monoxide with about the stoi- 5 tion mass.

Re'terences titted by'the Examiner UNITED STATES PATENTS 2,904,398

5/59 Smith 23-205 X 1 2,946,668 7/60 Richelsen 23-20 5 X 0 3,006,730 10/61 McCloskey etal 23-205 MAURICE A; BRINDISI, Primary Examiner. 

